The broad long-term objectives of the investigation pertain to a clearer understanding of both the relationship between accommodation and the optic array (dioptric and non-dioptric aspects), and the role of accommodation in the perceptual process. As part of the investigation we will examine the degree to which the visual system is sensitive to light vergence, and the possibility that dioptric information contributes to perception. Preliminary findings suggest that accommodation may not simply be a passive peripheral mechanism for maintaining a clear retinal image, but that it may participate more actively as part of the perceptual process. The research will use a high-speed infrared optometer to monitor accommodation, and a versatile stimulus system to manipulate a variety of dioptric stimuli and non- dioptric depth cues. Specifically the aims of the investigation are to (1) monitor the accommodative response to color fringes that simulate those produce when a target moves towards and away from eh eye; (2) determine the spatial frequencies at which chromatic aberration of the eye has the strongest effect on accommodation; (3) use ambiguous figure-ground displays composed of simulated blur-spread functions to examine the degree to which dioptric information might help specify the layout of the environment; (4) examine the possibility that accommodation receives primary input through magnocellular-type path-ways; (5) examine the relative importance of changing target size and apparent motion in depth on the accommodative response; (6) create highly realistic three- dimensional images that appear to move towards and away from the subject, to determine the extent to which pictorial cues can influence accommodation. A clearer understanding of the accommodative process, its relationship to dioptric and non-dioptric aspects of the optic array, and its role in the perceptual process, could have broad implications for the treatment of a variety of vision anomalies, including accommodative infacility, myopias, and amblyopia.